1. Field of the Invention
The present invention relates to a technique of controlling an element constituting a virtual world, in the virtual world.
2. Description of the Related Art
In a virtual world, a three-dimensional virtual space created by a server on a network is shared by multiple users' client terminals. In this virtual world, a character (hereinafter, referred to as an avatar) representing a user can move freely in the space, and can enjoy the virtual world, as if the virtual world were an extension in the real world, by communicating with the avatars of other users and by shopping. The virtual world is especially characterized in such a way that a large number of users from a wide variety of various places join the virtual world that a user can communicate with various unknown users in real time.
While allowing a user to communicate with an unspecified number of users, the virtual world is desired to provide an opportunity to communicate only among specified users. Japanese Patent Application Publication No. 2002-215553 describes a technique of constructing and controlling a space for a meeting, a lecture or the like, suited to communicate with specific users.
To be more precise, a moderator establishes a space, and has an authority to control operations executed by browsers of all users in the space. Types of such space include (1) a class room type, (2) a round table type, (3) a self-schooling type and (4) a compound type of a class room type and a round table type. In any type of space, all the avatars except for the moderator are not allowed to exchange information with another avatar outside the space. In (2) the round table type, participating users share information and are allowed to exchange information with each other through their avatars. In addition, the authority given to each avatar limits a range of the reach of a message from the avatar and a range of browsers controllable by the avatar. As described above, the conventional technique enables the access control for avatars existing inside the space by constructing and managing the space.
Accordingly, there are several problems with establishing and controlling a space in a virtual world. One problem is collision (interference) between objects belonging to a space and objects such as avatars existing inside the virtual world. As a result, the space itself and the objects are so restricted that they cannot operate or act flexibly. Moreover, it is difficult to allow only a remote avatar to enter the space by expanding the space, since an unnecessary avatar existing on the way to the remote avatar also inevitably enters the space. Another problem is that controllable accesses are limited. For example, controllable accesses can be limited only to accesses across the boundary of the space.
The aforementioned technique enables control only for accesses across the boundary of the space, but the access control for each object is needed in the virtual world. This is because a wide variety of objects exist in the virtual world and have different desires. Furthermore, in a virtual world, it is necessary to perform not only access control but also controls for communication information, visual information and information on object movements.